weathering

1. Weathering causes the disintegration
of rock near the surface of the earth.
Plant and animal life, atmosphere and
water are the major causes of
weathering. Weathering breaks down
and loosens the surface minerals of
rock so they can be transported away
by agents of erosion such as water,
wind and ice. There are two types of
weathering: mechanical and chemical.

2.  Chemical weathering
 Biological weathering
 Physical weathering

3.  Chemical weathering transforms the original
material into a substance with a different
composition and different physical
characteristics. The new substance is typically
much softer and more susceptible to agents of
erosion than the original material. The rate of
chemical weathering is greatly accelerated by
the presence of warm temperatures and
moisture. Also, some minerals are more
vulnerable to chemical weathering than others.
For example, feldspar is far more reactive than
quartz.

5.  Sometimes called mechanical
weathering, physical
weathering is the process that
breaks rocks apart without
changing their chemical
composition. These examples
illustrate physical weathering:

7.  Biological weathering is the weakening and
subsequent disintegration of rock by plants,
animals and microbes. Growing plant roots can
exert stress or pressure on rock. Although the
process is physical, the pressure is exerted by
a biological process (i.e., growing roots).

9.  DATE: 9-FEBRUARY-2015
 NAME:AHMED ALI
 CLASS:VIII-B

10. THANK YOU